Hitherto, as separators for non-aqueous electrolyte batteries, for example, JP-A-6-325747 discloses microporous films comprising a high molecular weight polyethylene having an intrinsic viscosity [.eta.] of 5 dl/g or higher. As separators for lithium cells, JP-A-3-105851 discloses microporous films comprising a composition composed of an ultra-high-molecular-weight polyethylene having a weight-average molecular weight of 7.times.10.sup.5 or higher and a polyethylene having a weight-average molecular weight/number-average molecular weight of 10-300.
These separators have a shut-down function for preventing ignition of batteries. The shut-down function is a function to prevent ignition due to melting of Li when electrodes cause external short-circuit and a great current passes therethrough to generate heat and the battery temperature reaches 180.degree. C. Specifically, separators melt before ignition of Li and result in clogging of open pore portions, whereby the battery reaction is stopped and generation of heat is inhibited. For example, the shut-down occurs at about 120.degree. C. when a porous body of polyethylene is used as a separator and at about 140.degree. C. when a porous body of polypropylene is used as a separator, and, as a result, generation of heat of battery stops to inhibit increase of temperature. However, in case much heat is generated which cannot be overcome by the shut-down function, melting of separator proceeds to cause complete melting of separators or cracking of separators, and as a result electrodes contact with each other, and thus a short-circuit current again flows, resulting in heat generation state, which leads to ignition.
Furthermore, these separators are relatively more uniform than the conventional nonwoven fabrics, but require complicated production steps and need high cost, and furthermore can hardly provide stable performance.
Recently, separators comprising nonwoven fabrics in place of microporous films are being developed from the points of easiness in production and stability of quality. For example, nonwoven fabrics for separators of batteries comprising specific fibers are disclosed in JP-A-5-74442 and JP-A-5-335005. However, when these nonwoven fabrics are used as separators, variation in thickness is greater than microporous films and adherence to electrodes constituting the batteries extremely decreases. Therefore, there is a problem that electrodes of sufficient volume cannot be incorporated into batteries in construction of batteries, and thus a satisfactory current capacity cannot be obtained when fabricated as a battery. Furthermore, in many cases, there occurs a slippage or a gap between electrode and separator in fabrication of batteries and processability is deteriorated.
The object of the present invention is to provide a nonwoven fabric for separators of non-aqueous electrolyte batteries and a non-aqueous electrolyte battery using the same in which adhesion of separators to electrodes is superior; there occurs no slippage or gap between electrode and separator; processability such as rollability with electrodes is excellent; no internal short-circuit occurs due to contact between electrodes or shrinking or burning of the nonwoven fabric even when the electrodes generate heat due to external short-circuit; ignition of batteries can be prevented; and a high current capacity and excellent battery characteristics and storage characteristics can be obtained.